Standard CMOS inputs are high impedance and are typically modeled as a resistor from the input to ground in parallel with the input capacitance given in the GUID-941836DA-3BC3-482C-98B8-9A7D6C596A61.html#GUID-941836DA-3BC3-482C-98B8-9A7D6C596A61. The worst case resistance is calculated with the maximum input voltage, given in the GUID-05CAE4DB-751B-4826-9CD0-5292B3842460.html#GUID-05CAE4DB-751B-4826-9CD0-5292B3842460, and the maximum input leakage current, given in the GUID-941836DA-3BC3-482C-98B8-9A7D6C596A61.html#GUID-941836DA-3BC3-482C-98B8-9A7D6C596A61, using ohm's law (R = V ÷ I).

The Schmitt-trigger input architecture provides hysteresis as defined by ΔV_T in the GUID-941836DA-3BC3-482C-98B8-9A7D6C596A61.html#GUID-941836DA-3BC3-482C-98B8-9A7D6C596A61, which makes this device extremely tolerant to slow or noisy inputs. While the inputs can be driven much slower than standard CMOS inputs, it is still recommended to properly terminate unused inputs. Driving the inputs slowly will also increase dynamic current consumption of the device. For additional information regarding Schmitt-trigger inputs, please see Understanding Schmitt Triggers.